Wetter than average conditions are likely for most of Australia over the next three months, according to the Bureau of Meteorology’s latest seasonal climate outlook issued this morning.

July to September rainfall is considered likely to above average across most of Australia.

However, southwest WA and western Tasmania have roughly equal chances of a wetter or drier three months.

July is likely to be wetter for most of Australia, except southwest WA.

The current outlook reflects the combination of a developing negative Indian Ocean Dipole, a continued cooling of tropical Pacific Ocean sea surface temperatures, and very warm sea surface temperatures surrounding northern and eastern Australia.

Historical outlook accuracy for July to September is moderate over most of Australia, but low in parts of the tropical north, near the WA border and central SA.

Cooler days likely for much of mainland Australia

Cooler than average days are more likely for most of the country for July to September. Warmer than average days are more likely for the tropical north and Tasmania.

Night-time temperatures for most of the southern mainland are more likely to be cooler than average. Warmer than average nights are more likely across the tropical north, eastern Victoria and Tasmania.

The current outlook reflects the combination of a developing negative Indian Ocean Dipole, a continued cooling of tropical Pacific Ocean sea surface temperatures, and very warm sea surface temperatures surrounding northern and eastern Australia.

Historical maximum temperature accuracy for July to September is moderate to high over most of Australia. Minimum temperature accuracy is moderate over northern Australia and Tasmania, but low elsewhere.

Early northern rainfall onset likely

The Bureau’s northern rainfall onset outlook is a guide to rainfall timing within the first months of the Australian northern wet season. The outlook is the percentage likelihood of the rainfall onset beginning earlier than normal.

The onset occurs when enough rain has fallen to stimulate plant growth after the dry season. This is the date after 1 September when a location has received total accumulated rainfall of at least 50 mm.

The outlook is updated monthly from June to August.

The statement issued on Thursday, June 30, rates the chance of an early northern rainfall onset for 2016–17 is higher than average over much of northern Australia.

The highest likelihood is over the Top End of the Northern Territory, Cape York Peninsula, the Kimberley and southeast Queensland

The current outlook reflects a warmer than normal Indian Ocean and the chance of La Niña in the second half of 2016